1. Field of the Invention
The present invention relates to a vehicle body frame structure in a vehicle, and in particular to improvements to a vehicle body frame structure of an all terrain vehicle.
2. Description of Background Art
A vehicle body frame for an all terrain vehicle is known which incorporates an upper frame, a lower frame and a down frame in a staged configuration. See, for example, FIG. 1 and FIG. 2 of JP-A No. 2008-114617. More specifically, as shown in FIG. 2 of JP-A No. 2008-114617, the vehicle body frame (4) (The figures in the brackets refers to reference numerals stated in JP-A No. 2008-114617. The same applies hereafter.) is constituted by two upper frames (31, 31), lower frames (32, 32) and down frames (35, 35).
In accordance with this type of vehicle body frame structure, an engine (5) as shown in FIG. 1 of JP-A No. 2008-114617 can be removed or installed from the side of the vehicle body. In other words, since the engine (5) that is a heavy body must be inserted from a space in the frame, a margin exists for improvement from an operational point of view.
Furthermore, since two upper frames (31) are arranged on the right and the left, there are a high number of frames, the structure of the frame of the vehicle body becomes complicated. Thus, an increase in the weight of the vehicle body frame occurs.
Consequently, there is a need for a vehicle body frame structure in which the weight can be reduced. In addition, there is a need to simplify the installation or removal processes of vehicle-mounted components such as the engine.